In an ideal world, we’d all eat a perfectly balanced diet every day, getting 100% of the vitamins and minerals we need from fresh, tasty, and home-cooked foods. In real life, however, that rarely happens. That’s where supplements come in—theoretically, at least.
For decades, we were taught that vitamins and minerals in pill form could help make up for deficiencies in the typical American diet, or provide health and energy boosts that food alone couldn’t. In recent years, however, many scientists have changed their tunes, as study after study shows no evidence that most popular supplements have any real health benefits.
That hasn’t stopped the industry from booming, however. Americans spend more than $30 billion a year on supplements, and more than half of adults have taken a supplement in the past 30 days, according to a 2016 study in JAMA. Many of them regularly take more than one, and some go to extremes: Celebrity chef Giada De Laurentiis recently told The Cut that she takes “20 pills a day” on the advice of her acupuncturist—“10 in the morning and 10 in the evening.”
But will all those supplements actually do you any good? And more importantly, is it possible to take too many vitamins? We posed those questions to health and nutrition experts, and dug into the latest research. Here’s what we learned.
The latest science on supplements
Scientists know that people who eat lots of vitamin- and mineral-rich foods tend to live longer and healthier lives. But when those nutrients are served up in pill form, it’s still unclear whether they have the same effect. For example, a major 2015 study found that taking dietary supplements does not appear to reduce the risk of cancer.
Several studies, including one published last month in the Journal of the American College of Cardiology, have also found that regular supplement use has no net effect on heart health or risk of early death.
“We found a surprising neutrality of effects,” lead author David Jenkins, MD, professor of medicine and nutritional sciences at the University of Toronto, told Health. “In other words, it didn’t seem to do anything.” Their findings were true for multivitamins as well as for vitamin C, vitamin D, and calcium supplements—all nutrients that have been touted for heart health in the past.
In light of these and other studies, most experts now say that dietary supplements aren’t all they were once made out to be. “For the average healthy person, you probably don’t need a multivitamin, multimineral supplement,” says Beth Kitchin, PhD, assistant professor of nutrition studies at the University of Alabama at Birmingham. “And you certainly don’t need a lot of additional supplements on top of that.”
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In moderation, most won’t hurt you—and, yes, some might help
That being said, Kitchin does believe that a multivitamin can help make up for some deficiencies in a person’s diet, especially if they avoid certain food groups like meat or dairy. She also recommends calcium and vitamin D supplements to some of her patients who are at risk of osteoporosis, “but I always look at their diet first before prescribing them,” she says.
Kitchin takes a daily multivitamin herself, but she actually only takes half a dose (one pill rather than a serving size of two). “I like to give myself a little extra insurance without overdoing it,” she says.
She tells her patients that, if they choose to take a multivitamin, to look for one with no more than 100% of the daily value for any one nutrient—and not to spend a lot of money, either. “There’s no strong evidence that it will help you, but as long as you keep the dose reasonable, it’s also not going to hurt you,” she says.
Dr. Jenkins agrees that, when taken in moderation, most vitamin and mineral supplements won’t cause harm. He also stresses that his recent study only looked at cardiovascular problems and early death, and that supplements may still have benefits in other areas.
“We didn’t look at overall health, we didn’t look at whether people got beautiful hair or skin, or whether your bones got stronger,” he says. “I’m not going to say that some supplements can’t be good for you in those ways.”
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You can definitely take too many
But just because supplements are safe in moderation doesn’t mean that more is better. Combining multiple supplements or taking higher-than-recommended doses can increase the risk that they can actually cause harm, says Kitchin. Plus, because the industry is not well regulated, there's no real guarantee that the ingredients and dosage on the label are accurate.
“You really can’t get toxic doses of nutrients through food, but you can absolutely get toxic doses through supplements,” she says.
Taking high doses of vitamin C can lead to stomach cramping and diarrhea, for example. High doses of vitamin A, vitamin D, and other nutrients can lead to more serious, long-term complications—like liver and kidney problems, or a dangerous hardening of blood vessels.
“We’ve learned a very important lesson, in that when we isolate these nutrients out of food and put them in super-high doses, we may have some unintended consequences,” Kitchin says. Plus, some supplement ingredients, including caffeine powder and red yeast rice, have been shown to be potentially dangerous even in low doses.
Even if none of your supplements individually exceeds the upper limit for a given nutrient, combining several pills—like a multivitamin and an additional vitamin D capsule, for example—may add up to higher-than-recommended doses. Supplements can also interact with each other, says Kitchin, or with medications you’re already taking.
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Always run things by your doctor
It’s a good idea to talk with your doctor about the supplements you’re taking on a regular basis, says Kitchin, especially if you have a health condition, a dietary restriction, or you’re on any type of medication. You should also run any new supplements you’re considering by your doctor or your pharmacist before you add them to your regimen.
It’s also important to focus on getting your nutrients from food first, says Dr. Jenkins, and not from supplements. “Pills are not a substitute for a good diet—plant-based, fruit, veggies, whole grains, nuts, and seeds,” he says. “They are packed with what you need.”
And while we’re here, a few more thoughts about those 20 pills that Giada apparently takes every day: The Food Network star elaborated that most of those supplements "switch out" day to day, but that she always takes a probiotic and a probiotic, along with vitamin D and biotin.
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It may be smart to work probiotics (healthy bacteria) and prebiotics (the nutrients that feed those good bugs) into your daily routine, but Kitchin says both of those can be found in foods, as well. “For the average healthy person, I would recommend eating things like yogurt and kefir,” she says. “Since we don’t have super-clear research yet, it’s hard to recommend specific supplements.”